This invention relates generally to electronics packaging and cooling techniques and, more particularly, to techniques for cooling integrated circuits in a space environment. There is a trend in the design of electronics for spacecraft toward more densely packed circuits, both at a component level and a chip level. This leads to an increase in power density and a high heat dissipation requirement. Cooling in a space environment must rely on conduction and radiation of heat from the packages, so many of the normal packaging techniques employing natural or forced convection do not work. In the past, spacecraft have simply used lower power densities. Complicated systems using pumped coolant have been proposed, but additional difficulties are likely to be introduced whenever anything other than passive cooling is used. Accordingly, there is still a need for a simpler solution to the cooling problems associated with high power density electronics in spacecraft. The present invention satisfies this need.